The usual way people farm this is to run Heroic Steamvault; however, cloth wearers will have severe trouble with this instance, even as a well geared level 80.
Another way is to buy Coilfang Armaments and turn them in, but this can get very expensive very fast. (This method was removed with the Cataclysm expansion.) Wouldn’t it be better if you made money with your reputation grind?
It turns out that there is a spot in Northrend where you can gain Cenarion Expedition reputation. The druids of D.E.H.T.A. have a repeatable quest to turn in Nesingwary Lackey Ears which grants 150 reputation for 15 ears. These are very easily farmable by any class from the Minion of Kaw in Borean Tundra, as I demonstrated in my first World of Warcraft video.
These mobs drop plenty of Frostweave Cloth, vendorable grays, and greens which will actually sell.